Method for producing a rubber composition comprising a rubber crumb
View Patent ↗A process for preparing a rubber composition based on at least one diene elastomer, a reinforcing filler, a crumb rubber and a crosslinking system is provided. The process comprises at least the following steps: incorporating the reinforcing filler into the diene elastomer, all at once or in several stages, and mixing; when the temperature of the mixture reaches a temperature of greater than 100° C., adding the crumb rubber; continuing the mixing up to a maximum temperature of between 120° C. and 190° C.; cooling the mixture to a temperature of less than 100° C.; incorporating the crosslinking system and mixing up to a maximum temperature of less than 110° C.
1 . A process for preparing a rubber composition based on at least one diene elastomer, a reinforcing filler, a crumb rubber and a crosslinking system, said process comprising at least the following steps A to E:
step A: Incorporating the reinforcing filler into the diene elastomer, all at once or in several stages, and mixing to form a first mixture,
step B: when the temperature of the first mixture reaches a temperature of greater than 100° C., adding the crumb rubber to form a second mixture,
step C: continuing the mixing of the second mixture up to a maximum temperature of between 120° C. and 190° C. to form a third mixture,
step D: cooling the third mixture to a temperature of less than 100° C. to form a fourth mixture,
step E: incorporating into the fourth mixture the crosslinking system and mixing up to a maximum temperature of less than 110° C. to form a fifth mixture.
2 . The process according to claim 1 , in which, during step A, the reinforcing filler is incorporated when the diene elastomer reaches a temperature of greater than 50° C.
3 . The process according to claim 1 , in which, during step B, the crumb rubber is added when the first mixture reaches a temperature of greater than 110° C.
4 . The process according to claim 1 , in which, during step C, the mixing is continued up to a maximum temperature of between 130° C. and 180° C.
5 . The process according to claim 1 , in which, during step D, the third mixture is cooled to a temperature of less than 80° C.
6 . The process according to claim 1 , in which steps A to C are carried out in a first mixer.
7 . The process according to claim 1 , in which steps A to C are carried out for a period of time within a range extending from 1 to 7 minutes.
8 . The process according to claim 1 , in which step E is carried out in a second mixer.
9 . The process according to claim 1 , in which step E is carried out for a period of time within a range extending from 5 to 15 minutes.
10 . The process according to claim 1 , in which the crumb rubber has an acetone extract of between 3% and 30% by weight.
11 . The process according to claim 1 , in which the crumb rubber has a chloroform extract of between 3% and 85% by weight.
12 . The process according to claim 1 , in which the crumb rubber has a ratio of the chloroform extract to the acetone extract, expressed as weight percentage, of less than 1.5.
13 . The process according to claim 1 , in which the diene elastomer is selected from the group consisting of polybutadienes, polyisoprenes, butadiene copolymers, isoprene copolymers and the mixtures of these elastomers.
14 . The process according to claim 1 , in which the diene elastomer is a mixture of at least two diene elastomers selected from the group consisting of polybutadienes, butadiene/styrene copolymers, and natural or synthetic polyisoprenes.
15 . The process according to claim 2 , in which, during step A, the reinforcing filler is incorporated when the diene elastomer reaches a temperature of greater than 80° C.
16 . The process according to claim 3 , in which, during step B, the crumb rubber is added when the first mixture reaches a temperature of greater than 120° C.
17 . The process according to claim 4 , in which, during step C, the mixing is continued up to a maximum temperature of between 140° C. and 170° C.
18 . The process according to claim 5 , in which, during step D, the third mixture is cooled to a temperature of less than 60° C.
19 . The process according to claim 6 , in which steps A to C are carried out in an internal mixer.
20 . The process according to claim 3 , in which, during step B, the crumb rubber is added when the first mixture reaches a temperature of greater than 140° C.